Real-time content filtering messaging

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At the Embedded Systems Conference, held in Boston this week, Real-Time Innovations (RTI) has introduced a preview of a new version of its real-time publish-and-subscribe messaging middleware, RTI Data Distribution Service.

New features include batch messaging and content-based delivery, said Edwin de Jong, an RTI director of product management

This middleware allows remote devices, such as those on a sensor network, to send out data feeds to multiple clients. The RTI DDS is a library that can be linked into the end-user application publishing the information, as well as into the data processing nodes that receive that information.

RTI DDS uses the Object Management Group's Data Distribution Service (DDS) set of specifications, as well as the Real-Time Publish-Subscribe Protocol (RTPSP), to guarantee real-time delivery of data. It can be used across a variety of platforms, such as Internet Protocol networks (where it uses User Datagram Protocol), shared memory systems and specialized networks, de Jong said.

Lockheed Martin uses the RTI DDS for the Aegis Weapon System, and Raytheon uses the middleware for the DDG 1000 shipboard systems.

RTI has added two new major features to the current version of the RTI DDS, which is being packaged as the first iteration of Version 4.4 of the product.

This is the first version to include content-based filtering, de Jong said. This means an end-device can determine which recipients should get a set of data that it produces based on the content itself. For instance, radar routinely collecting data on aircraft movements can send an update to security office only if it spots an aircraft flying into some restricted zone.

The system builder would determine which data fields the software should monitor and what the values would cause the system to send such messages, as well as what other recipients they should be sent to, de Jong said.

Another new feature is batch messaging, or the ability to bundle multiple messages into a single data packet. For systems using networks that require fixed packet sizes, such as Ethernet-based networks, bundling small messages into packets'rather than devoting a full packet to each message'can conserve bandwidth and even end-user processor utilization, de Jong said.

In addition to the preview version of RTI DDS, RTI has also introduced a slimmed-down version of the libraries that could meet the FA-178B specification, used by the Federal Aviation Administration and other avionics concerns to ensure that the software can be used in safety-critical operations.

The Air Force Research Laboratory commissioned RTI to develop this version of the library, called the RTI DDS Safety Critical Edition to use on satellites, de Jong said. The work mostly consisted of removing unneeded functions from the library, which is only about 130 kilobytes in size in this iteration.

This edition has not been certified to a certain level of FA-178B, de Jong said. A system integrator could, however, incorporate this middleware into a larger system that would go through such an evaluation, he added.

RTI DDS Safety Critical Edition will work on Linux, Solaris, VxWorks 5.5 and VxWorks 6.4 operating systems, and can be ported to other real-time OSes as well.

About the Author

Joab Jackson is the senior technology editor for Government Computer News.